The European patent document EP 1 645 434 A1 discloses an arrangement for the timed processing of book blocks, composed of printed sheets, wherein these are frequently composed either of individual sheets or folded signatures. The aforementioned publication proposes assigning a lifting device provided with end stop to the feed element. With the aid of the lifting device, a supplied book block is pivoted from a horizontal position to a vertical position and is then transferred with the help of an adjustably driven end stop to the clamp of the perfect binder. With this sequence of operational steps, book blocks supplied while positioned horizontal can be transferred without problem and avoiding additional changeover movements to a perfect binding station. In the process, the book block is placed into the upright position by the lifting device and is inserted from below into a perfect binder clamp. The lifting movement is initiated before a book block arrives at the end stop, wherein the adjustability of the end stop can also be utilized for adjusting the format of the supplied book block. However, it has turned out that with such an operating sequence, the cycle time or the cadence is subject to relatively strong limitations. As a result, it is no longer possible to achieve higher timing rates because the underlying sequence is configured such that a return lift is first required before a new book block is advanced, meaning before it can be taken over.
In principle it has turned out that a book block can be supplied along an advancing plane only over the course of a plurality of processing cycles for which a longer feed section is required.
Several solutions are already disclosed for correcting this problem. However, these solutions on the whole did not satisfy since a partial improvement in each case could be achieved only with additional structural measures, which in turn had a negative effect on the susceptibility of the system.
For example, it was necessary to assign a guide element that is positioned at a distance to the guide rails forming the guide plane in order to prevent the possible tilting to one side of the book block at the end stop. This guide element supports and guides the book block on the opposite side.
To be sure, the book blocks can be pivoted with the aid of a gear assembly that is drive-connected to the end stop from the horizontal position on the feed element to a vertical position in which it rests on the book block spine, but this can be done only if corresponding additional guide rails are provided.
To prevent a tilting, the different book block thicknesses furthermore require an adjustment of the distance between the guide plane formed with the guide rails and the guide element. Unfortunately, this can be achieved with respect to kinematics only if a traction mechanism is provided.
It must furthermore be considered that at the instant of feeding the book block, meaning when the aforementioned lifting device is in the starting position, the guide rails must advantageously be positioned below the conveying center of the conveying elements, which are supported gliding on supports, to avoid friction between the book blocks and the guide rails, wherein this requires additional measures.
As a result of these point-by-point considerations, we can state that all the modifications disclosed so far involve a relatively large expenditure and have not always yielded the initially expected results, so that we now feel pressured to take new paths and provide new suggestions for developing an arrangement for the timed processing of book blocks composed of at least one printed sheet. It may be taken into consideration here that the book blocks may be composed of loose sheets, meaning the printed sheets are not securely joined to each other. Of course, it is also possible to use book blocks where the printed sheets are joined ahead of time.